Within the field of parting and grooving of a rotating metal workpiece, a cutting insert may be secured in a blade shaped insert holder, and the insert holder in turn releasably retained in a tool holder. The tool holder typically comprises a main block with a longitudinal channel or groove, and a means of clamping the insert holder within the longitudinal channel or groove.
U.S. Pat. No. 5,031,492 and U.S. Pat. No. 5,079,979 each disclose a tool holder, where an insert holder is clamped within a main block by means of a single clamping member. The clamping member forms an upper wall of a longitudinal groove and interfaces with an upper ridge shaped surface of the insert holder. Several clamping screws pass through holes in the clamping member and into corresponding threaded bores in the main block. A clamping operation is performed by rotating the clamping screws until each applies a sufficient clamping force between the insert holder and a lower wall of the longitudinal groove of the main block. The clamping forces are released by rotating the clamping screws in an opposite direction. They both employ at least three clamping screws thereby requiring the screwing of at least three screws. They both require approach from the top to tighten the screws, which may not always be possible.
U.S. Pat. No. 3,531,842 discloses a tool holder, where a cutting insert and support blade are clamped within a main block by means of a single wedge shaped clamping member. The wedge shaped clamping member is positioned against an upper wall of a longitudinal groove of the main block and interfaces with an upper surface of the cutting insert. A means of clamping actuation is provided by a double threaded member interfacing with corresponding threaded bores in the main block and the wedge shaped clamping member. A clamping operation is performed by rotating the double threaded member, which causes the wedge shaped clamping member to move in a longitudinal direction relative to the main block, until a sufficient clamping force is applied between the cutting insert and support blade and a lower wall of the longitudinal groove of the main block. The clamping force is released by rotating the double threaded member in an opposite direction. Although the clamping operation is performed by a single means of clamping adjustment, this solution has a limited flexibility of configuration in that the cutting insert can only operate from one end of the main block. Also, clamping is provided along only a short section of the longitudinal groove, thus limiting the distance that the cutting insert and support blade can be extended beyond the main block and acceptably perform a parting and grooving operation.